Article grasping device for fork lift trucks



June 10, 1969 w, HOWARD Y 3,448,880

ARTICLE GRASPING DEVICE FOR FORK LIFT muons 7 Filed Feb. 23. 1966 Sheetof 4 INVENTOR WILL/AM E. HOWARD A T TORNE VS June 10, 1969 w. E. HOWARDj 3,448,380

ARTICLE GRASPING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23, 1966 Sheet 2of 4 FIG.& 2 I42 June 10,-1969 w. E. HOWARD 3,448,880"- ARTICLE GRASPING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23. 1966 Sheet 3 M4 103. ,I i0 /l0 1 I J/ M m 102 I 42 m 6 as "$6 58 40 32" FIG 9 I I 82 86 v 32 l 7488 0"} I 1 0 I02 a 1m 70 {03 as 92 l c 102 54 58 54, 1 I :5? 5-7 I f7 36F' I G. 7

June 10, 196 9 w. E. HOWARD 3,448,880

ARTICLE GRASPING DEVICE FOR FORK LIFT TRUCKS Filed Feb. 23. 1966 Sheet 40f 4 FIGJQG United States Patent US. Cl. 214-620 9 Claims ABSTRACT OFTHE DISCLOSURE A device attachable to the fork of a fork lift truckpermits the truck to grasp, pick up and release an article such as adrum while the operator remains on the truck and without the need for anassistant or powered parts. Two opposing article grasping pads arelocated on the two prongs of the fork for movement about vertical axesbetween spread article receiving positions and closed article graspingpositions, and are biased toward the article receiving positions so thatas an empty fork is moved toward an article the engagement of the padswith the article moves the pads toward their article grasping position.The pads are additionally supported for rotation about axes which arecoaxially arranged when the pads are in their article grasping positionsto allow the pads and the article grasped thereby to be rotated afterthe article is picked up by raising the fork. The pads are alsosupported by carriers which swing about horizontal axes generallyparallel to the fork prongs. During an article receiving process thepads are swung upwardly about these latter axes to increase the spacingbetween the pads, and as the fork is thereafter raised the weight of thearticle swings the pads downwardly about these axes to decrease thespacing therebetween and to thereby cause the article to be firmlgrasped.

This invention relates to fork lift trucks, and deals more particularlywith a device usable with a fork lift truck to enable the truck to graspand lift a relatively rigid article.

Conventionally, fork lift trucks are operated to lift articles byinserting the fork of the truck beneath the article or beneath a palleton which one or more articles are loaded, the fork when liftedvertically supporting the article by engaging the bottom of the articleor pallet. When no pallets are used, this method of operation requireseither that the articles handled be manually loaded onto and off of thefork or that some special provision be made for allowing the fork topass freely under the articles during loading and unloading. To overcomethis problem, an object of this invention is the provision of a devicewhereby a fork lift truck, when used to handle relatively rigid articlesof a fairly uniform size and shape, may engage and grasp such an articleat its sides, and with sufficient clamping force to enable the articleto be lifted and manipulated without slipping, thereby eliminating theneed for pallets, manual loading or other special provisions. Throughthe use of a device embodying this invention, a fork lift truck may beused to pick up andreplace an article directly from or onto a floor orsimilar flat surface without the operator leaving the truck and withoutany other manual assistance.

In some of its aspects, the invention may be embodied in a deviceconstructed and adapted solely to lift articles, but a further object ofthe invention is to provide a device of the foregoing character wherebythe article after being grasped and lifted may be rotated about agenerally horizontal axis to change the orientation of the article. Inkeeping with this object, a more specific object is to pro- 3,448,880Patented June 10, 1969 vide a device of the foregoing characterespecially adapted to handle open-topped trash drums or similarcontainers, so that without leaving the truck an operator may pick up acontainer, carry it to another point, rotate it to dump its contents,and then replace it at will at any convenient location in its normalupright position.

Another object of this invention is to provide a device of the foregoingcharacter which may be made as a simple attachment to a standard forklift truck and which uses the normal movements of the truck to elfectthe grasping, release and rotation of the ,handled article, therebyeliminating the need for any additional motors or actuators andassociated control mechanisms,

Other objects and advantages of the invention will be apparent from thefollowing description and from the drawings forming a part hereof.

The drawings show a preferred embodiment of the invention and suchembodiment will be described, but it will be understood that variouschanges may be made from the construction disclosed, and that thedrawings and description are not to be construed as defining or limitingthe scope of the invention, the claims forming a part of thisspecification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a side elevational view of a fork lift truck equipped with anarticle grasping device of this invention and adapted for handlingdrums, this view showing the device in its article grasping positionrelative to a drum resting on the ground;

FIG. 2 is a view generally similar to FIG. 1, but shows the device withthe drum raised from the ground and rotated to a dumping position;

FIG. 3 is an enlarged top view of the article grasping device of FIG. 1,the device in this view being shown in its empty or article receivingposition;

FIG. 4 is a view similar to FIG. 3, but showing the article graspingdevice in its article grasping position;

FIG. 5 is a still further enlarged top view of one of the pressure padassemblies of the article grasping device of FIG. 1, the pressure padassembly in this view being shown in its article grasping position;

FIG. 6 is a vertical sectional view taken on the line 66 of FIG. 5;

FIG. 7 is a vertical sectional view taken on the line 7--7 of FIG. 6;

FIG. 8 is a view generally similar to FIG. 5, but shows the pressure padassembly with the parts thereof in the positions occupied at a pointintermediate the article receiving and article grasping positions;

FIG. 9 is a vertical sectional view taken on the line 9-9 of FIG. 8;

FIGS. 10a, 11a, 12a and 13a are simplified or schematic front end viewsof the article grasping device of FIG. 1 and show the sequence ofmovements involved in moving the device into grasping relation with adrum;

FIGS. 10b, 11b, 12b and 13b are simplified or schematic top viewscorresponding respectively with the end views of FIGS. 10a, 11a, 12a and13a.

Turning now to the drawings and first considering FIGS. 1, 2, 3 and 4, adevice embodying the present invention is shown attached to aconventional fork lift truck 12 having a vertical mast 14 at its forwardend. The mast 14 includes a stationary part of column 16 and avertically movable part or column 18, the movable part 18 having fixedthereto a fork 20, the portion of the movable part to which the liftingfork is attached being often referred to as a lifting carriage. Raisingand lowering movement of the column 18 relative to the column 16, toraise and lower the fork 20, is effected by one or more hydraulicactuators or other conventional motors controlled by the operator of thetruck by means of a control lever 22 mounted on the steering column 24,or elsewhere near the steering column, so as to be easily manipulated bythe operator while he remains in a driving position on the truck. Thefork is of conventional construction and, as shown best in FIGS. 3 and4, includes two horizontal and transversely spaced prongs 26, 26 whichextend forwardly from the mast 14.

The article grasping device of this invention is carried by the prongs26, 26 of the fork 20 and includes two pressure pad assemblies,indicated generally at 28 and 30. The pressure pad assemblies 28 and 30are substantially identical to one another, are associated respectivelywith the two fork prongs 26, 26, and are located directly opposite toone another near the forward ends of the prongs. Each pressure padassembly includes a pressure pad 32 having an article engaging surface34 conforming generally to the shape of the side surface of the articleto be handled. In the illustrated case, the device is designed for usein handling steel drums, such as the one indicated at 36 in the variousfigures, and therefore the pressure pads 32, 32 are arcuately curved toprovide arcuately curved article engaging surfaces 34, '34 conforminggenerally to the circular shape of the side walls of the drums which arehandled. It should be understood, however, that the invention is notnecessarily limited to the handling of drums or other generallycylindrical articles and that by using differently shaped pressure padsarticles of other shapes may also be handled. For example, by usingpressure pads with substantially planar article engaging surfaces thedevice of the invention may be used to handle articles such asrectangular boxes having flat vertical side surfaces.

FIG. 3 shows the pressure pad assemblies 28 and 30 in their articlereceiving positions, and when the assemblies are in such positions thepressure pads 32, 32 are in a generally forwardly diverging relationshipto one another so that their forward edges 38, 38 are spaced apart by adistance greater than the thickness of drum 36. Therefore, the drum 36in FIG. 3 may be moved to a position between the pressure pads by movingthe pressure pad assemblies 28 and 30 forwardly toward the drum, thisbeing accomplished by the operator driving the fork truck 12 forwardly.As explained in more detail hereinafter, the pressure pad assemblies 28and 30 are movable, by engagement with the drum 36, from the receivingpositions of FIG. 3 to the grasping positions of FIG. 4. When in theirgrasping positions, the pressure pads 32, 32 engage diametricallyopposite sides of the drum 36, and the spacing between the articleengaging surfaces 34, 34 is slightly less than the normal outsidediameter of the drum so that the drum is slightly deformed when graspedto produce a large clamping force between the pressure pads and thedrum, this in turn creating sulficient friction between the pressurepads and the drum to prevent the drum from slipping vertically relativeto the pressure pads as the pressure pads are raised to lift the drum.

In addition to use for merely grasping and lifting a drum from theground or other support, the pressure pad assemblies 28 and 30 are alsodesigned to permit rotation of the pressure pads 32, 32 about a commontransverse axis, after the drum is grasped and raised, for dumping thecontents of the drum or for any other purpose. To illustrate thisfeature, FIG. 1 shows the drum 36 grasped by the grasping device of thisinvention but with the fork 20 in a lowered position at which the drumrests in its normal position on the ground. From this position, the drumis movable to the position shown in FIG. 2 at which it is raised fromthe floor and inverted. The drum 36 may, for example, as is often donein machine shops, have an open top and be used as a container forreceiving scrap or trash. The device of the invention is thereforeconveniently used for picking up such drums and for rotating them todump their contents into another larger receptacle or conveyance.

The pressure pad assemblies 28 and 30 may be directly attached to theassociated fork prongs 26, 26, but as shown in the illustrated case,they are preferably carried by a separate frame which fits over theprongs and which is quickly and easily attached to and removed from theprongs to allow the truck 12 to be quickly converted from normal use touse with the grasping device, and vice versa. The frame may take variousdifferent forms and as shown comprises two channel members 40, 40 eachof which in use overlies and receives a respective one of the prongs 26,26. Each channel member 40 is slightly shorter than the associated prongand extends from the forward end of.the prong to a point spaced slightlyfrom the vertical rear portion of the prong. To the top surface of eachchannel member is Welded a spacer plate 42 which extends rearwardlybeyond the channel member and which is engageable with the vertical rearportion of the prong to properly locate the channel member on the prong.

The two channel members 40, 40 are connected to one another by a thirdchannel member 44 extending transversely between the members 40, 40 andwelded at each end to the adjacent member 40. For releasably holding theframe to the fork prongs, each channel member 40, adjacent its rear end,threadably receives a retaining screw 46 provided with a handle enablingit to be easily turned by hand. Each screw 46 passes through theassociated channel member 40 and is engageable at its lower end with thetop surface of the associated prong. Directly beneath each retainingscrew, as shown in FIGS. 1 and 2, the associated channel member 40includes a plate 48 extending transversely across the bottom of theprong and welded to the side flanges of the channel member. Therefore,by tightening the screw 46 the associated prong is tightly clampedbetween the screw 46 and the associated plate 48 to firmly retain theframe on the prongs.

The details of the construction of the pressure pad assemblies 28 and 30may be best understood by reference to FIGS. 3 to 9. FIGS. 5 to 9 areenlarged views of the right-hand assembly 30, and the left-hand assembly28 is substantially an exact mirror image counterpart of the right-handassembly except that the assembly 30 includes a semi-circular segment 50of a V-grooved pulley used in cooperation with a cable 52 to rotate thepressure pad assemblies, as described in more detail hereinafter.Referring to these figures, each pressure pad assembly inchides a baseplate 54 which rests flatly on top of another bearing plate 56 welded tothe top surface of the associated channel member 40. Adjacent thelaterally inner edge of the bearing plate is a vertical pivot pin 58which isfixed to the bearing plate 56. The pin 58 extends upwardlyloosely through an opening in the base plate 54 and restrains the latterto pivoting movement relative to the associated prong 26 about thevertical axis of the pivot pin 58. Welded to the channel member 40adjacent thelaterally outer edge of the bearing plate is an L-shapedretaining member 57 having an upper horizontal leg, see FIGS. 6 and 9,which is spaced above the bearing plate to form a channel for receivingthe laterally outer end portion of the base plate 54. This latter leg ofthe member 57 is therefore engageable with the base plate to prevent itsouter end from being moved upwardly by the weight of the drum.

Movement of the base plate 54 about the pivot pin 58 is limited tomovement between the two positions shown in FIGS. 3 and 4, and suitablestop-means are provided for arresting the movement of the base plate inboth directions. In the illustrated case, these stop means include anupstanding lug 58 provided on each channel member 40 behind theassociated base plate and engageable with the base plate, as shown inFIG. 3, to limit the movement of the base plate toward its articlereceiving position. Another stop lug 60 extends upwardly from theforward edge of each bearing plate 56 and is engageable with theadjacent edge of the base plate to limit the movement of the base platein the direction toward its article grasping position of FIG. 4. Eachbase plate is biased toward the article receiving position of FIG. 3 bya helical tension spring stretched between the base plate and an arm onthe associated stop lug 58.

The base plate 54 of each pressure pad assembly includes two verticallyextending ears 64 and 66 which are spaced from one another along thelength of the associated channel member 40 when the base plate is in thearticle grasping position shown in FIGS. 4, 5 and 8. Between the twobase plate ears 64 and 66 is a U-shaped carrier 68 having two upwardlyprojecting legs spaced laterally from one another when the base plate 1sin ts article grasping position. Adjacent the bottom of its laterallyouter leg the carrier 68 is pivotally connected to the ears 64, 66 ofthe base plate by a horizontal plvot pin 70. The carrier 68 is thereforecapable of pivotal movement relative to the base plate about the ax s ofthe pivot pin 70 between a normal or lowered position, as shown in FIG.6, and a raised position, as shown 1n FIG. 9. Movement of the carriertoward the raised position of FIG. 9 is arrested by a stop post 71carried by the base plate ear 66.

The carrier 68 rotatably supports an intermediate part 72 for rotationabout an axis located above and arranged generally perpendicular to theaxis of the pivot pin 70.

More particularly, the intermediate part 72 includes a' generallycylindrical shank portion 74 which passes loosely through conformingopenings in the two arms of the carrier so as to be rotatable relativethereto. The shank portion 74 is externally threaded along a part of itslength and is axially fixed relative to the carrier by a thrust bearing76, two locking nuts 78, 78 and a collar 80, the collar 80 beingreleasably fixed to the outer end of the shank portion by a set screw orsimilar means. ThlS arrangement allows the intermediate part 72 to bemoved to various different positions of axial adjustment relative to thecarrier 68, by shifting the locking nuts 78, 78 and the collar 80, tovary the spacing between the two pressure pads 32, 32 to allow thedevice to be used for handling drums or other articles of variousdifferent sizes. In FIG. 5, for example, the solid lines show thepressure pad 32 at one position of adjustment of the intermediate part72, and the broken lines show the same pad at another adjusted positionof the intermediate part.

At its inboard end the intermediate part 72 of each pressure padassembly includes a head 82 having two flat parallel side surfacesengaged respectively by two parallel spaced ears fixed to the pressurepad '32 and pro ecting laterally outwardly therefrom. The pressure pad32 is pivotally connected to the head 82 by a pivot pm 86 passingthrough the cars 84, 84 and through the head 82. Normally the pin 86 ispositioned with its axis horizontal and parallel to the axis of thecarrier pivot pm 70. As shown in FIGS. 6 and 9, the movement of thepressure pad relative to the head 82 is limited in both directions bytwo generally inwardly facing surfaces 88 and 90 on the inner end of thehead 82, the surface 88 being engageable with the outer surface of thepad 32 to limit movement of the pad in one direction and the surface 90being engageable with the outer surface of the pad to limit its movementin the other direction. A biasing spring 92 is received in a blindopening in the head '82 and works between the head and the pressure pad32 to urge the pressure pad to the position shown in FIG. 6 whereat themovement of the pad is arrested by the stop surface 88, the pad 32 inthis position being generally perpendicular to the axis of theintermediate part 72. In FIGS. 6 and 9 the pad ear 84 facing the viewerhas been omitted to more clearly show the structure of the head '82 andthe arrangement of the spring 92.

As mentioned, the pivot pin 86 is normally parallel to the pivot pin 70,and to hold the head 82 in the position required to achieve thisorientation of the pin 86, a biasing means is provided between thecarrier 68 and the intermediate part 72. In the illustrated case, thisbiasing means, as shown best in FIG. 7, comprises a spiral torsionspring '94 surrounding the shank portion 74 of the part 72 and having aradially inwardly directed inner end received in an axially elongatedslot 96. The outer end of the spring is formed into a circular loopsurrounding a post 98 fixed to the inboard leg of the carrier. As theintermediate part 72 is adjusted axially relative to the carrier 68, theinner end of the spring 94 may slide in the slot 96. The spring 94 is sodesigned as to have a normal undeformed shape such as shown in FIG. 7 sothat when no torque is imposed between its ends the spring holds theintermediate part 72 in the FIG. 9 position. The spring 94 thereforeresists movement of the intermediate part 72 in either direction aboutits axis from its neutral position at which the pivot pin 86 ishorizontal and parallel to the pin 70. When the pressure pads 32, 3-2are rotated, however, to invert the grasped article, the twointermediate parts 72, 72 are rotated about their axes and the twosprings 94, 94 are deformed and provide a restoring force for laterreturning the article to its normal position.

As will be evident from FIG. 4, when the two pressure pad assemblies 28and 30 are in their article grasping positions, the axes of the twointermediate parts 72, 72 are colinear so that the drum 36 or othergrasped article may be rotated by rotating the two parts 72, 72simultaneously about their common axis. The means for effecting therotation comprises the previously mentioned V- grooved pulley segment 50which is welded or otherwise secured to the outwardly facing side of theassociated pressure pad 32. The segment 50' is arranged, generallyconcentric with the axis of the part 72. It is approximately 180 inangular extent and is located forwardly of a vertical plane passingthrough the axis of the part 72, when the pressure pad is positioned asin FIG. 1. The cable '52 normally passes over the pulley segment 50 andhas its outer end fixed to a lug 99 attached to the outer surface of thepad 32 adjacent the upper end of the segment 50. From the bottom end ofthe segment 50 the cable 52 passes rearwardly through a housing 100*containing a roller or pulley 101 and beyond the housing '100 has itsrear end fixed to the stationary column 16 of the mast 14, theattachment point being shown at 104.

Referring to FIGS. 1 and 2, the drum 36, as it is lifted from the FIG. 1position, retains its upright or FIG. 1 orientation until all slack istaken up in the cable 52. Thereafter, continued raising of the fork 20causes the cable to be pulled from the segment 50, rotating the segmentand in turn rotating the pressure pads and the drum to the FIG. 2position or to any other position involving a lesser degree of rotation,the amount of rotation depending upon the height to which the fork israised.

Each pressure pad assembly 28 and 30 also includes a catch device forreleasably holding the base plate 54- of the assembly in its articlegrasping position and which catch is released in response to the upwardswinging movement of the associated carrier 68. In the illustrated case,this catch device comprises a latch member 102 pivotally connected tothe horizontal leg of the associated retaining member 57 by a pivotscrew 10'5 passing vertically loosely through the forward end of thelatch 102 and threaded at its lower end into the retaining member 57, aspacer 106 being received on the screw 104 between the member 57 and thelatch 102 to space the latch 102 some distance above the retainingmember 57. A torsion spring 103 biases the latch member 102 about thepivot screw 104 toward the latched position shown in FIG. 5 and resistsits movement in the opposite direction. In FIGS. 5 and 6, the carrier 68is shown in its lowered position and when the carrier is in thisposition, a finger 108 on the rear end of the latch member is engageablewith the rearwardly [facing surface of the base plate ear 66 to hold thebase plate in its article grasping position. The latch member 102 isfurther so designed so as to include a laterally inwardly extendingswell or protrusion 110 which is engageable with the outwardly facingsurface of the outer leg of the carrier 68. When the carrier 68 is movedto its raised position, as shown in FIGS. 8 and 9, the outer leg of thecarrier 68, by engagement with the swell 110, moves the latch 102outwardly to an unlatched position relative to the base plate ear 66 sothat the base plate is thereafter free to move to its article receivingposition.

Before turning to a more complete description of the operation of thedevice, it should be noted, by referring to FIGS. 6 and 9, that thearrangement of the parts is such that from the article grasping positionof FIG. 6 the pressure pad 32 may be moved in the direction away fromthe grasped article, and away from the opposite pressure pad, bysimultaneously rotating the carrier 68 about its pivot pin 70 androtating the pressure pad 32 about its pivot pin 86 to the positionsshown in FIG. 9.

Having now described the construction of the illustrated device, itsoperation may be more easily understood by reference to FIGS. 10a to 13bwhich somewhat schmetically show the device at various stages in theprocess of moving into grasping relationship with a drum. Turning tothese figures, FIGS. 10a and 10b show the device with the pressure padassemblies in their article receiving positions and moved to a pointwhereat the drum 36 is partially received between the pressure pads 32,32. This position is reached by the operator of the truck 12 moving thetruck forwardly toward the drum. At this time the operator of the truckalso controls the elevation of the fork so that the two pressure pads32, 32 are located at such a height as to be vertically positionedbetween the two chimes 112, 112 of the drum.

The operator then drives the truck further forwardly to cause thepressure pads 32, 32 to engage the drum and to thereby rotate the twobase plates 54, 54 part way toward the final article grasping positionsof FIG. 4. Before such final positions are reached, however, thepressure pads 32, 32 reach the positions of FIGS. 11a and 11b whereatthe engagement of the pressure pad with the drum tends to resist furtherrotation of the base plates. When this position is reached, the operatorlowers the fork of the truck slightly to the position shown in FIG. 12aand while doing so also moves the truck still further forwardly relativeto the drum. The lowering of the fork causes the carriers 68, 68 of thetwo pressure pad assemblies to be swung to their raised positions toincrease the space between the pressure pads, thereby allowing thefurther forward movement of the truck which rotates the base plates tothe positions shown in FIG. 12b. During the movement of the parts fromthe FIG. 11a to the FIG. 12a positions, the pressure pads 32, 32 areprevented from moving downwardly relative to the drum by engagement withthe lower barrel chime 112 and/or by the friction existing between thepressure plates and the drum.

After the base plates 54, 54 are moved to the positions shown in FIG.12b, the operator again raises the fork to the position shown in FIG.13a. As this latter movement takes place the carriers 68, 68 arereturned to their normal lowered positions, and as a result of this thepressure pads 32, 32 are moved inwardly toward the drum and tightlyclamp the drum therebetween as shown in FIG. 13b. As the final articlegrapsing position of FIGS. 13a and 13b is reached, the two latches 102,102 of the two pressure pad assemblies move to their latched position toprevent rotation of the base plates. Thereafter, the fork may be raisedabove the level of FIG. 13a to lift the drum from the ground or floorand, as previously described, after the drum is raised to a given point,the cable 52 and segment 50 operate to rotate the drum for dumping itscontents or for other purposes.

After the drum 36 has been lifted by the device of this invention, itmay be disengaged from the device and placed in a normal position on theground or other supporting surface by following the reverse proceduredescribed in connection with FIGS. 11a to 1311. That is, the fork isfirst lowered to bring the bottom end of the drum to rest against theground and is then lowered further to raise the carriers 68, 68 to thepositions shown in FIG. 12a, the raising of the carrier to this positionspreading the pressure pads 32, 32 to remove the clamping pressure fromthe drum and also moving the associated latches 102, 102 from theirlatched conditions. The operator then may back the truck 12 away fromthe drum 36 and as this i done, the pressure pads 32, 32 slide aroundthe outer surface of the drum and they and the associated base platesare moved to the article receiving positions of FIG. 10b and FIG. 3 bythe associated tension springs 62, 62, the drum thereby being releasedfrom the grasping device and the device conditioned for use in receivingand grasping another drum.

From this description of the operation of the device. it will beunderstood that the operator of the truck may operate the truck to causethe device to grasp a drum or other article, to lift the article, todump the drum, to return the drum to its normal position, and to then release the device from engagement with the drum, all without the operatorleaving the truck 12 or requiring any manual assistance. It should alsobe noted that the height at which the drum 36 is rotated for dumping maybe readily controlled by varying the length of the operating cabel 52and/or by fixing the rear end of the cable to different points along thelength of the stationary column 16.

Returning to FIGS. 3 and 4, these figures show an alternative meanswhich may be used in conjunction with, or in place of, the stop lugs 60,60 for limiting the move ment of the base plates 54, 54 to their articlereceiving positions. This alternative means comprises a cable 112 havingits opposite ends fixed to lugs 114, 114 located respectively adjacentthe rear edges of the two pressure pads 32, 32. The cable 112 is of suchlength as to be slack when the pressure pad assemblies are in thearticle receiving positions of FIG. 3, and when the pressure pads aremoved to their article grasping position relative to the drum 36, thecable 112 is stretched tightly between the lugs 114, 114 and against therear surface of the drum to prevent further movement of the pressure padassemblies and also to positively prevent the drum from movingrearwardly beyond the position shown in FIG. 4. It should also be notedthat the pressure pads 32, 32 in the illustrated example are preferablycomprised of curved pieces of plate steel with the inner surfaces of thesteel pieces forming the article engaging surfaces 34, 34. If desired,however, the inner surfaces of the steel pieces may be lined with rubberor other material for increasing the friction between the pads and thearticles to be handled. Such friction increasing material is not,however, necessary in the illustrated case since the chimes 112, 112 ofthe drums being handled positively prevent any undue slippage betweenthe drums and the pressure pads while the drum is lifted.

In the case of some fork lift trucks such as small trucks of thenon-riding type, the forks customarily used with the trucks may havetheir prongs too closely spaced to accommodate the drums or otherarticles to be lifted. The present invention may however be readily usedwith such trucks by removing the conventional fork and using a prongedframe which is attached directly to the lifting carriage or equivalentpart of the truck in place of the conventional fork, the prongs of theframe in turn carrying the pressure pad assemblies in the same manner asthe prongs of the illustrated frame. It should therefore be understoodthat in the claims which follow the term fork is used to refer to eitherthe fork conventionally used with the truck or to a special fork shapedframe attached to the truck in place of the conventional fork.

The invention claimed is:

1. An article grasping device for use with a fork truck having avertically movable fork with two generally horizontal transverselyspaced prongs, said device when attached to such a fork truck comprisingtwo pressure pads each associated with a respective one of said prongs,said pressure pads being located directly opposite from one another andhaving generally vertical article engaging surfaces generally facing oneanother, and having a shape conforming generally to the side surfaces ofthe article to be grasped, means supporting each of said pressure padsfor movement about a generally vertical axis to permit said pads to bemoved between article receiving positions and article graspingpositions, said two pads when in their article receiving positionshaving their article engaging surfaces diverging forwardly so that theforward edges thereof are transversely spaced by a distance greater thanthe thickness of the article to be grasped and said two pads when intheir article grasping positions being I arranged to engage oppositesides of said article, means supporting each of said pressure pads forswinging movement upwardly and laterally outwardly relative to theassociated prong during movement of said pads from said articlereceiving positions to said article grasping positions to increase thespacing between said pads and to thereby allow said pads to looselyreceive said article therebetween, said pads when said fork isthereafter raised being swung downwardly and laterally inwardly by theweight of said article to decrease the spacing between said pads and tothereby cause said pads to tightly grip said article therebetween, meanssupporting said pressure pads for movement about a common axis extendingtransversely of said prongs when said pads are in their article graspingpositions, and means for rotating said pads about said common axis torotate the grasped article in response to vertical movement of said forkafter said fork is raised above a predetermined level.

2. An article grasping device for use with a fork truck having avertically movable fork with two generally horizontal transverselyspaced prongs, said device when attached to such a fork truck comprisingtwo pressure pads each associated with a respective one of said prongs,said pressure pads being located directly opposite from one another andhaving generally vertical article engaging surfaces generally facing oneanother, and having a shape conforming generally to the side surfaces ofthe article to be grasped, means supporting each of said pressure padsfor movement about a generally vertical axis to permit said pads to bemoved between article receiving positions and article graspingpositions, said two pads when in their article receiving positionshaving their article engaging surfaces diverging forwardly so that theforward edges thereof are transversely spaced by a distance greater thanthe thickness of the article to be grasped and said two pads when intheir article grasping positions being arranged to engage opposite sidesof said article, means supporting each of said pressure pads forswinging movement upwardly and laterally outwardly relative to theassociated prong during movement of said pads from said articlereceiving positions to said article grasping positions to increase thespacing between said pads and to thereby allow said pads to looselyreceive said article therebetween, said pads when said fork isthereafter raised being swung downwardly and laterally inwardly by theweight of said article to decrease the spacing between said pads and tothereby cause said pads to tightly grip said article therebetween, meanssupporting said pressure pads for movement about a common axis extendingtransversely of said prongs when said pads are in their article graspingpositions, means for biasing said pads to a normal angular positionrelative to said common axis, and means for rotating said pads and thegrasped article about said common axis and against the biasing force ofsaid biasing means in response to raising movement of said fork beyond apredetermined level, said biasing means serving to rotate said pads andthe grasped article back to said normal position of said pads uponsubsequent lowering movement of said fork.

3. An article grasping device as defined in claim 2 furthercharacterized by said means for rotating said pads comprising an arcuatemember fixed to one of said pads in concentric relation to said commonaxis, and a flexible tension member having one end fixed relative tosaid arcuate member and its other end fixed to a part of said truckwhich is stationary relative to said fork, said flexible tension beingtrained over a part of said arcuate member when said pads are in saidnormal position and being so arranged as to be pulled off of saidarcuate member as said fork is raised above a given level relative tosaid stationary part of said truck.

4. An article grasping device for use with a fork truck having avertically movable fork with two generally horizontal transverselyspaced prongs, said device when attached to such a fork truck comprisingtwo pressure pads each associated with a respective one of said prongs,said pressure pads being located directly opposite from one another andhaving generally vertical article engaging surfaces generally facing oneanother, and having a shape conforming generally to the side surfaces ofthe article to be grasped, means supporting each of said pressure padsfor movement about a generally vertical axis to permit said pads to bemoved between article receiving positions and article graspingpositions, said two pads when in their article receiving positionshaving their article engaging surfaces diverging forwardly so that theforward edges thereof are transversely spaced by a distance greater thanthe thickness of the article to be grasped and said two pads when intheir article grasping positions being arranged to engage opposite sidesof said article, means supporting each of said pressure pads forswinging movement upwardly and laterally outwardly relative to theassociated prong during movement of said pads from said articlereceiving positions to said article grasping positions to increase thespacing between said pads and to thereby allow said pads to looselyreceive said article therebetween, said pads when said fork isthereafter raised being swung downwardly and laterally inwardly by theweight of said article to decrease the spacing between said pads and tothereby cause said pads to tightly grip said article therebetween, saidmeans supporting each of said pressure pads for movement about agenerally vertical axis comprising a base member supported on theassociated prong for movement about said vertical axis, latch means forreleasably holding said base member in the position corresponding to thearticle grasping position of the associated pressure pad when said padis in its downwardly swung position, and means for releasing said latchmeans in response to the upward swinging movement of said pad to allowsaid base member to be moved to the position corresponding to thearticle receiving position of the associated pressure pad.

5. An article grasping device as defined in claim 4 furthercharacterized by biasing means associated with each of the base membersof the two pressure pads for biasing said base members to the positionscorresponding to said article receiving positions of said pressure pads.

6. A device for use with a fork truck having a vertically movable forkwith two generally horizontal trans versely spaced prongs, said devicewhen attached to such a fork truck comprising two pressure padassemblies located respectively on said two prongs directly oppositefrom one another for releasably grasping an article receivedtherebetween, each of said pressure pad assemblies including a basesupported for movement relative 'to the associated prong about agenerally vertical axis fixed relative to said associated prong betweenan article receiving position and an article grasping position, acarrier pivotally connected with said base for movement between raisedand lowered positions about a generally horizontal carrier axis fixedrelative to said base, said carrier axis when said base is in itsarticle receiving position being generally parallel to said associatedprong, a pressure pad for engaging the adjacent side of an articlereceived between said pressure pad assemblies, means pivotallyconnecting said pressure pad to said carrier to enable said pad topivotally move relative to said carrier about a horizontal axis parallelto said carrier axis as said carrier is swung between its raised andlowered positions, means for biasing said base to its article receivingposition, a catch for holding said base in its article grasping positionwhen said carrier is in its lowered position, and means for releasingsaid catch to allow movement of said base about said vertical axis, inresponse to movement of said carrier from its lowered to its raisedpositions.

7. A device as defined in claim 6 further characterized by. said meansfor connecting said pressure pad to said carrier comprising anintermediate part carried by said carrier and supported thereby forrotation about an axis which is hoizontal when said carrier is in itslowered position and which is in a plane perpendicular to said carrieraxis, means for biasing said intermediate part to a normal angularposition relative to said carrier, and means pivotally connecting saidpressure pad to said carrier for movement about an axis which isparallel to said carrier axis when said intermediate part is in itsnormal angular position.

8. A device as defined in claim 7 further characterized by means foradjustably positioning said intermediate part to various differentpositions along its axis relative to said carrier to vary the spacingbetween the two pressure pads of said two pressure pad assemblies.

9. A device as defined in claim 7 further characterized by meansassociated with one of said pressure pad assemblies for rotating itsintermediate part relative to the associated carrier, when an article isgrasped between said pressure pad assemblies, in response to verticalmovement of said fork above a predetermined level.

References Cited UNITED STATES PATENTS 2,683,546 7/1954 Sherriff 214-6522,706,060 4/1955 Ferrario 214-652 2,713,431 7/1955 Koehler 214-7102,755,949 7/1956 Sehenkelberger 214-653 2,812,089 11/1957 Purpura214-620 2,842,275 8/1958 Kughler 214-653 2,877,911 3/1959 Arnot 214-1472,877,913 3/1959 Arnot 214-147 2,915,332 12/1959 Cotesworth 294-106 X3,112,835 12/1963 Gierhart 294-110 X 3,180,512 4/1965 Moss 214-6203,319,815 5/1967 Vik 214-620 FOREIGN PATENTS 1,150,322 6/1963 Germany.

GERALD M. FORLENZA, Primary Examiner.

R. B. JOHNSON, Assistant Examiner.

US. Cl. X.R.

